( CNN) Here’s a look at the National Guard, a reserve military force and the oldest ingredient of the US armed forces.

The National Guard was formed in 1636 as the militia of the colonists in North America, and is guaranteed by the US Constitution .

The Marquis de Lafayette, on a visit to the United States in 1824, popularise the term “national guard” as a description for the various states’ militias. The title was formalized by federal legislation in 1903.

Recent Wartime International Mobilizations:

Timeline of Domestic and Other Federal Mobilizations: